rocks and minerals
by:aaron leake

sedimentary rock

1.) this is limestone. Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate (CaCO3). Most limestone is composed of skeletal fragments of marine organisms such as coral. 2.) Flint is a hard, sedimentary rock form of the mineral quartz, categorized as a variety of chert. It occurs chiefly as nodules and masses in sedimentary rocks, such as chalks and limestones. 3.) Earth's most important iron ore deposits are found in sedimentary rocks. They formed from chemical reactions that combined iron and oxygen in salt and fresh waters. The two most important minerals in these deposits are iron oxides: hematite and magnetite. 4.)Sandstone  is a clastic sedimentary rock composed mainly of sand sized minerals or rock grains. Most sandstone is composed of feldspar because these are the most common minerals in the Earth's crust. 5.) Conglomerates are sedimentary rocks consisting of rounded fragments and are thus differentiated from breccias, which consist of angular clasts. Both conglomerates and breccias are characterized by clasts larger than sand.

Igneous Rocks

1.)Diorite  is a grey to dark-grey intermediate intrusive igneous rock composed principally of plagioclase feldspar typically andesine, biotite, hornblende, and/or pyroxene. 2.)A pegmatite is a holocrystalline, intrusive igneous rock composed of interlocking phaneritic crystals usually larger than 2.5 cm in size; suchrocks are referred to as pegmatitic. Most pegmatites are composed ofquartz, feldspar and mica, having a similar basic composition as granite. 3.) Gabbro refers to a large group of dark, often phaneritic coarse-grained, mafic intrusive igneous rocks chemically equivalent to plutonic basalt. It forms when molten magma is trapped beneath the Earth's surface and slowly cools into a holocrystalline mass. 4.) The term 'granite' also applies to a group of intrusive igneous rocks with similar textures and slight variations on composition and origin. These rocks mainly consist of feldspar, quartz, mica, and amphibole minerals. 5.) Obsidian is a naturally occurring volcanic glass that forms as an extrusive igneous rock. It is produced when felsic lava extruded from a volcano cools rapidly with minimum crystal growth.

Metamorphic Rock

1.) Phyllite is a type of foliated metamorphic rock created from slate that is further metamorphosed so that very fine grained white mica achieves a preferred orientation. It is primarily composed of quartz, sericite mica, and chlorite. 2.) Marble is a metamorphic rock form composed of coarse crystals from parent limestone or dolostone rocks. Pure marble is white and composed of the mineral calcite. It has been very popular for sculpture and building construction because of its beauty and relative softness. 3.) Gneiss is a high grade metamorphic rock, meaning that it has been subjected to higher temperatures and pressures than schist. It is formed by the metamorphosis of granite, or sedimentary rock. 4.)  Schist is medium grade metamorphic rock, formed by the metamorphosis of mudstone  shale, or some types of igneous rock, to a higher degree than slate, i.e. it has been subjected to higher temperatures and pressures. 5.) Soapstone also known as steatite, or soap rock  is a talc-schist, which is a type of metamorphic rock. It is largely composed of the mineral talc and is thus rich in magnesium.